1/*
2 * Copyright (C) 2012, 2013 Apple Inc. All Rights Reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 *
25 */
26
27#include "config.h"
28#include "DocumentSharedObjectPool.h"
29
30#include "Element.h"
31
32namespace WebCore {
33
34inline unsigned attributeHash(const Vector<Attribute>& attributes)
35{
36 return StringHasher::hashMemory(attributes.data(), attributes.size() * sizeof(Attribute));
37}
38
39inline bool hasSameAttributes(const Vector<Attribute>& attributes, ShareableElementData& elementData)
40{
41 if (attributes.size() != elementData.length())
42 return false;
43 return !memcmp(attributes.data(), elementData.m_attributeArray, attributes.size() * sizeof(Attribute));
44}
45
46Ref<ShareableElementData> DocumentSharedObjectPool::cachedShareableElementDataWithAttributes(const Vector<Attribute>& attributes)
47{
48 ASSERT(!attributes.isEmpty());
49
50 auto& cachedData = m_shareableElementDataCache.add(attributeHash(attributes), nullptr).iterator->value;
51
52 // FIXME: This prevents sharing when there's a hash collision.
53 if (cachedData && !hasSameAttributes(attributes, *cachedData))
54 return ShareableElementData::createWithAttributes(attributes);
55
56 if (!cachedData)
57 cachedData = ShareableElementData::createWithAttributes(attributes);
58
59 return *cachedData;
60}
61
62}
63